when people are in the shower, especially in the winter, it needs to firstly drain the cold water in the water pipe, until there is warm water out, then begin the shower, the traditional way of discharge cold are manually controlled way, that is, the valve is been switched to the warm water state until the cold water in the water row finished, and in some areas even it take a few minutes to discharge cold water, in this discharge cold method it needs to touch and feel the water temperature, need to waste time specifically for waiting, or the people will be frozen to cold water, if not guarding nearly, there may be a waste of hot water resources.
The utility model patent 201521135958.8 discloses a switching valve having a discharge cold function, which is provided with a discharge passage for controlling the communication between the head water outflow passage and the discharge cold passage so that the residual cold water in the head water outflow passage can be discharged from the discharge cold passage; the discharge cold passage is closed when the water is discharged normally. In order to achieve this technical effect, the head water outflow passage and the discharge cold passage are opened and closed by a one-way valve and a reset spring. First of all, because the one-way valve is in the normally closed state, when discharging cold, it needs a certain suction to open the one-way valve, the required suction must be able to overcome the spring force and one-way valve and Y-ring friction; secondly, when discharging cold, the venturi effect is used, the resulting suction is parallel to the direction of one-way valve movement, but the cross-sectional area difference is very small, that is, the action area on the one-way valve corresponding to the suction is small, so the downward force on the one-way valve by is also very small, when the pressure is less than a certain value, it simply can not open the one-way valve, and can not discharge the cold water of the top spray water; so that the flow area of the cooling section is very small, the flow is very small, greatly extending the time of the discharging cold; In addition, in the process of using the hand shower, once the hand shower is with a small flow of water or water stop function, resulting in increased pressure inside the discharging cold channel, the water flowing through the hand shower from the suction hole to the top spray, so that top spray water spills, so the whole structure is not reliable.